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The generation of sound by aerodynamic sources in an inhomogeneous steady flow

Published online by Cambridge University Press:  29 March 2006

M. S. Howe
M. S. Howe
Affiliation:
Engineering Department, University of Cambridge
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Abstract

This paper examines the effect of steady flow on the generation of sound by aerodynamic sources located in the neighbourhood of a scattering body. The analysis is facilitated by the use of a reverse-flow reciprocal theorem which is valid for a certain class of inhomogeneous flow problems. In the case of acoustic ‘bremsstrahlung’, in which sound is generated during the passage of a silent fluid inhomogeneity, such as an entropy spot, past an obstacle in the flow, an elegant discussion of the interaction can be given in terms of a renormalized Green's function. Here the effect of the obstacle is equivalent to a local distortion of the geometry of the three-dimensional space occupied by the medium, the extent of which governs the properties of the acoustic radiation. This is illustrated by means of a detailed analysis of the sound generated during the unsteady convection of a source of constant strength through a neck in a duct.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 67 , Issue 3 , 11 February 1975 , pp. 597 - 610
Copyright
© 1975 Cambridge University Press

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